Influence of wetting conditions on bubble formation from a submerged orifice

The formation of gas bubbles by submerged orifices is a fundamental process encountered in various industrial applications. The dynamics of the contact line and the contact angle may have a significant influence on the detached bubble size depending on the wettability of the system. In this study, the influence of wetting conditions on the dynamics of bubble formation from a submerged orifice is investigated experimentally and numerically. The experiments are performed using a hydrophobic orifice plate and a series of ethanol–water solutions to vary the wettability where the key characteristics of the bubbles are measured using a high-speed, high-resolution camera. An extensive analysis on the influence of wetting conditions on the bubble size, bubble growth mechanism and the behavior of the contact line is given. Bubble growth stages, termed (1) hemispherical spreading, (2) cylindrical spreading, (3) critical growth and (4) necking, are identified based on key geometrical parameters of the bubble and relevant forces acting on the bubble during the growth. The experimental results show that the apparent contact angle varies in a complicated manner as the bubble grows due to the surface roughness and heterogeneity. The experimental findings are finally used to validate the local front reconstruction method with a contact angle model to account for the contact angle hysteresis observed in the experiments. Graphic abstract: [Figure not available: see fulltext.

An improved subgrid scale model for front‐tracking based simulations of mass transfer from bubbles

Gas–liquid bubble column reactors are often used in industry because of their favorable mass transfer characteristics. The bubble mass boundary layer in these systems is generally one order of magnitude thinner than the momentum boundary. To resolve it in simulations, a subgrid scale model will account for the sharp concentration variation in the vicinity of the interface. In this work, the subgrid scale model of Aboulhasanzadeh et al., Chem Eng Sci, 2012, 75:456–467 embedded in our in‐house front tracking framework, has been improved to prevent numerical mass transfer due to remeshing operations. Furthermore, two different approximations of the mass distribution in the boundary layer have been tested. The local and global predicted Sherwood number has been verified for mass transfer from bubbles in the creeping and potential flow regimes. In addition, the correct Sherwood number has been predicted for free rising bubbles at several Eötvös and Morton numbers with industrial relevant Schmidt numbers (103–105)

Data underlying: Fourier mode analysis for effective diffusion in coarse porous media via direct numerical simulations

This package contains a code for 3D resolved simulations of diffusion-reaction in randomized coarse porous media and the associated data. Throughout the simulations, the Fourier modes with n = 1-5 are determined and stored

Comparison of the local front reconstruction method with a diffuse interface model for the modeling of droplet collisions

In the present study the authors compare two different simulation models for the modeling of droplet collisions. The simulation models are: the Local Front Reconstruction Method (LFRM) and the Diffuse Interface Model (DIM). Results for fully three-dimensional simulations of droplet collisions at relatively high Weber number simulated with both models are presented and compared. Additionally, a detailed analysis of the dissipation and energy transfer processes of the collision is presented. An overall good agreement is seen in the collision outcomes. Some differences are observed in the interface evolution and the energy transfer/dissipation process during the droplet collision. A significant portion of these differences can be attributed to the differences in the configuration of the initial velocity field. Therefore, for the initial configuration a divergence-free vortical velocity field is introduced to achieve a better match between the simulation models. This improves the agreement of the simulation results

Matlab fig files for paper Analysis of Particle-Resolved CFD Results for Dispersion in Packed Beds

This is a dataset consisting of Matlab .fig files corresponding to the figures in the paper 'Analysis of Particle-Resolved CFD Results for Dispersion in Packed Beds' published in the MDPI journal fluids. In this paper dispersion of an inert tracer injected in a slender packed bed is investigated by means of particle-resolved CFD simulations. Three figures show post-processed full-field data of porosity, velocity and concentration fields. Longitudinal dispersion is characterized using cummulant residence time distributions for different axial positions. This data is used to compute axial dispersion coefficients. From the spread in the radial direction as function of the axial position, transverse dispersion is obtained. The .fig files can be used to make high quality plots but also contain the data

Matlab fig files for the article: Experimental study on vibrating fluidized bed solids drying

This is a set of Matlab .fig files corresponding to the figures in the paper 'Experimental study on vibrating fluidized bed solids drying' published in Chemical Engineering Journal. In this study, experiments in a pseudo-2D vibro-fluidized bed setup are performed in order to better understand this improved drying behavior. A coupled particle image velocimetry - infrared thermography technique is applied to characterize the local solids velocity and temperature fields. This data-set provides the post-processed temperature characteristics dependent on operation conditions of the vibrating fluidized bed

Data underlying: Modeling the drying process of porous catalysts - impact of viscosity and surface tension

This package contains the Mathworks MATLAB scripts, associated input files, generated results and visualization via Originlab Origin which are related to the publication 'Modeling the drying process of porous catalysts - impact of viscosity and surface tension' in Chemical Engineering Scienc

Matlab fig files for 'the paper 'A detailed gas-solid fluidized bed comparison study on CFD-DEM coarse-graining techniques'

This is a set of Matlab .fig files corresponding to the figures in the paper 'A detailed gas-solid fluidized bed comparison study on CFD-DEM coarse-graining techniques' published in Chemical Engineering Science.In this study, we critically compared the coarse-graining scaling laws of Mu et al. [2020, Chemical Engineering Science: X 6.] and Sakai and Koshizuka [2009, Chemical Engineering Science: 64, 533–539.] for their effectiveness in characterizing a fluidized bed

Matlab fig files for the paper 'Experimental gas-fluidized bed drying study on the segregation and mixing dynamics for binary and ternary solids'

This is a set of Matlab .fig files corresponding to the figures in the paper 'Experimental gas-fluidized bed drying study on the segregation and mixing dynamics for binary and ternary solids' published in Chemical Engineering Journal. In this study, experiments in a pseudo-2D fluidized bed setup were performed to obtain insight in the complex and changing bed hydrodynamics and its interplay with mass and heat transfer. The data was obtained by using a combined Particle Image Velocimetry (PIV), Digital Image Analysis (DIA) and Infrared (IR) technique. Furthermore, a machine learning algorithm was applied in order to determine the segregation and mixing dynamics. The dataset consists of the following .fig files whereof a short description is given below: Figure 3: Minimum fluidization velocity determination using the mean pressure drop over the bed. Figure 4: Precision-recall analysis Figure 8: Segregation index based on the average height of the medium and large-sized solids.Figure 9: Segregation index based on the average height of the medium and large-sized solids.Figure 10 A, B, C and D: Time-averaged solids volume fluxes for the u0=0.975 m/s drying case at four different times.Figure 11 A, B, C and D: Time-averaged solids volume fluxes for the u0=1.17 m/s drying case at four different times.Figure 12 A, B, C and D: Time-averaged solids volume fluxes for the u0=1.365 m/s drying case at four different times.Figure 13 A and B: Mean particle temperature and standard deviation over time for the three different superficial gas velocities. Figure 17 A and B: Segregation indices based on the average height of the small, medium and large-sized solids.Figure 18 A, B, C and D: Time-averaged solids volume fluxes for the u0=0.7875 m/s drying case at four different times.Figure 19 A, B, C and D: Time-averaged solids volume fluxes for the u0=0.945 m/s drying case at four different times.Figure 20 A, B, C and D: Time-averaged solids volume fluxes for the u0=1.1025 m/s drying case at four different times.Figure 21 A and B: Mean particle temperature and standard deviation over time for the three different superficial gas velocities

Performance study of heat and mass transfer in an adsorption process by numerical simulation

In this work, a detailed three dimensional model is employed for the quantitative description of flow and coupled heat and mass transfer in a gas channel coated with porous adsorbent layer. The flow field of the gas stream is obtained by solving the Navier-Stokes equation. The highly coupled mass and heat transfer in both the gas channel and the adsorbent layer are locally described, and the accompanying adsorption/desorption dynamics in the adsorbent layer are modelled as well. A parametric study has been carried out, in which the influences of thermal conductivity of the adsorbent layer, specific heat, porosity, tortuosity, layer thickness and geometrical shape on the performance of moisture adsorption processes are investigated in an exhaustive way. The heat and mass transfer mechanisms in the investigated cases are thoroughly analysed taking advantage of the rigorous 3D model, which deepens our understanding on the intricately coupled transport processes. The results reported in this work are useful for rational design and optimization of adsorption processes in adsorbent coated gas channels